feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

backend/infra/config/env.ts

@@ -0,0 +1,21 @@
+/**
+ * Environment Configuration
+ * Load and validate environment variables
+ */
+
+export const config = {
+  port: parseInt(process.env.PORT || '3000', 10),
+  nodeEnv: process.env.NODE_ENV || 'development',
+  apiBaseUrl: process.env.API_BASE_URL || 'http://localhost:3000',
+  
+  // Database
+  dbUrl: process.env.DATABASE_URL || 'postgresql://localhost:5432/microdao',
+  
+  // Auth
+  jwtSecret: process.env.JWT_SECRET || 'change-me-in-production',
+  
+  // Wallet/Chain (future)
+  chainRpcUrl: process.env.CHAIN_RPC_URL || '',
+};
+
+

backend/infra/db/client.ts

@@ -0,0 +1,20 @@
+/**
+ * Database Client
+ * MVP: Placeholder for future DB connection
+ * TODO: Replace with actual DB client (PostgreSQL, etc.)
+ */
+
+// MVP: No-op
+export const dbClient = {
+  connect: async () => {
+    // TODO: Implement actual DB connection
+    console.log('[DB] Connected (stub)');
+  },
+  
+  disconnect: async () => {
+    // TODO: Implement actual DB disconnection
+    console.log('[DB] Disconnected (stub)');
+  },
+};
+
+

backend/infra/db/dao.repository.ts

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+/**
+ * DAO Repository
+ * Database access layer for DAO records
+ * MVP: In-memory storage, replace with actual DB later
+ */
+
+import type { DaoRecord } from '../../domain/dao/types';
+
+// MVP: In-memory storage
+const daoStore: Map<string, DaoRecord> = new Map();
+
+export const daoRepository = {
+  async save(record: DaoRecord): Promise<void> {
+    daoStore.set(record.daoId, record);
+  },
+
+  async findById(daoId: string): Promise<DaoRecord | null> {
+    return daoStore.get(daoId) || null;
+  },
+
+  async findAll(filter?: { level?: string; type?: string }): Promise<DaoRecord[]> {
+    const all = Array.from(daoStore.values());
+    
+    if (!filter) {
+      return all;
+    }
+
+    return all.filter(dao => {
+      if (filter.level && dao.level !== filter.level) {
+        return false;
+      }
+      if (filter.type && dao.type !== filter.type) {
+        return false;
+      }
+      return true;
+    });
+  },
+
+  async delete(daoId: string): Promise<void> {
+    daoStore.delete(daoId);
+  },
+};
+
+

backend/infra/logger/logger.ts

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+/**
+ * Logger
+ * MVP: Simple console logger
+ * Future: Replace with proper logging library (Winston, Pino, etc.)
+ */
+
+type LogLevel = 'info' | 'warn' | 'error' | 'debug';
+
+export const logger = {
+  info: (message: string, ...args: unknown[]) => {
+    console.log(`[INFO] ${message}`, ...args);
+  },
+  
+  warn: (message: string, ...args: unknown[]) => {
+    console.warn(`[WARN] ${message}`, ...args);
+  },
+  
+  error: (message: string, ...args: unknown[]) => {
+    console.error(`[ERROR] ${message}`, ...args);
+  },
+  
+  debug: (message: string, ...args: unknown[]) => {
+    console.debug(`[DEBUG] ${message}`, ...args);
+  },
+};
+
+